Preparation of keto-amine salts in the steroid series and products



Patented Sept. 4, 1951 PREPARATION OF KETO-AMINE SALTS IN THE STEROID SERIES AND PRODUCTS Percy L. Julian, Maywood, and Edwin W. Meyer and John W. Cole, Chicago, and Arthur Magnani, Wilmette, 111., assignors to The Glidden Company, Cleveland, Ohio, a corporation of No Drawing. Application August 28, 1947,

Serial No. 771,136

25 Claims. (01. 260-3973) The present invention relates to the preparation of keto-amine salts of the steroid series and to certain intermediates in their preparation. More particularly the invention relates to such compounds in which the amine group'is attached either directly to the 17-carbon atom of the steroid nucleus or contained in a side chain attached to the l'l-carbon atom of the steroid nu cleus.

Such amines are valuable intermediates in the preparation of known compounds possessing physiological activity and as possible therapeutic agents themselves.

Several attempts to isolate and purify such keto amines by the methods described in the literature have shown that these amines have a strong tendency to pass over into arnorphous insoluble. condensation products. Due to this fact none of these keto -amines has heretofore been isolated as pure, compounds and characterized. It is believed that these condensations result from reaction between the keto-group of one molecule and the amine group of another molecule. These amorphousproducts cannot be purifled by recrystallization, and further reactions are impractical because of their insolubility and lack of purity.

It is accordingly an object of the present invention to accom lish the purification of'such keto-1amines in the. form of suitable derivatives.

Another object of the invention is to provide an improved process for preparing keto-ainine salts in the steroid series.

An additional object is to provide new derivatives of keto-amines in the steroid series useful in accomplishing the foregoing objects.

Other objects will be apparent to those skilled in the art from the'iollowing description.

The realization of these objects involves preparing the desired derivatives of the keto-amines indirectl without passin through the unworkable free keto-amines. This has been accomplished by (1) conden ing the corresponding hydroxy-amines witharomatic aldehydes to form Schifis bases, (2 oxidising the hydroxyeschiffs bases to the kctc-Schitis b nd n (3) hrdrolyzing the Schiffs bases to the keto-amine salts with Q1 without purification of the keto Schifis bases.

The emplo ment oi th h droxy-s h f bases otters two advan es F st. hey are easi y of the same product.

crystallizable substances and result in effecting a purification of the hydroxy-ramines. Secondly, during the oxidation the ketoeschifis bases which are formed are stable and do not. lead to the amorphous condensation products characteristic of the free keto-amine. Furthermore, the resulting keto-Schiffs bases are easily crystallizable substances which make possible a practical separation and purification of the products. It has proved to be advantageous to purify the ketc- Schiffs bases before hydrolysis to the pure ketoamine sales, rather than to attempt a purificas tion of the salts. Many of the latter are hygroe scopic water-soluble substances which, although they are crystalline products, do not readily lend themselves to purification by recrystallization.

The hydrolysis of the purified ketO-Schifis bases comprises heating'them with aqueous. acid with subsequent removal of; the liberated aldehyde by either steam distillation or by solvent extraction. The solution of the amine salt may be evaporated if it is desired to obtain the crystalline salt. A variety of acids have been used, f example, hy roch ric. a et hosp oric a tartaric.

The mostv suitable method for oxidizing the hydroxy-Schifis bases has been by the use of aluminum alcoholate-ketone mixture, commonly classified as the Qppenauer method, but other oxidation and dehydrogenation'methods for converting the hydroxy group to a keto group may be employed.

The following exanngles are illustrative of the invention:

Example 1 Ten grams of 3-hydroxy-.l'hamino-S-androstene was dissolved in '70 cc. of hot ethanol, then to the clear solution was added a mixture of 5 g. of benzaldehyde and 10 cc. of ethanol. After several seconds crystals began to form in the hot solution. The solution was cooled, filtered, and the solid product was dried, yielding 11.1 g. of white crystals of 3-.hydroxy!17+benzaldimino- E-androstene, having a ineltingpoint of 239-241 C. The mother liquor yielded an additional 0.2 g.

m i??? 3 Ten grams of 3-hydroxy-17-benzaldimino-5- androstene, 30 cc. of cyclohexanonaand cc. o uene were heat d to a lea so tion. the

a small amount of the solvent was distilled to carry oil? any trace of moisture that may have been present. Then a solution of 10 g. of aluminum isopropoxide in 100 cc. of hot toluene was added, and the mixture waskept hot over a steam bath for three hours. The mixture was cooled, diluted with ether, washed three times with cold 15% sodium hydroxide, washed three times with water, then the drained ether-toluene layer was steam distilled to remove the ether, toluene and cyclohexanone. The residue after cooling was a suspension of waxy crystals of 3-keto-17-benzaldimino4androstene. It may be purified by recrystallization from ether plus alcohol, from which it separates slowly as white crystals melting at 176-178 C.

Example 3 The crude waxy crystals of 3-keto-17-benzaldimino-l-androstene obtained as described above are dissolved in 150 cc. of methanol and treated with 20 cc. of 18% hydrochloric acid. The resulting solution is steam distilled briefly to remove benzaldehyde and part of the methanol, and then the residue is cooled and extracted once with benzene. The resulting water drochloride ismade up of white granular, slightly hygroscopic crystals which decompose when heated.

In an analogous manner, other salts of the keto-amine were obtained by hydrolyzing 3- keto-l'l-benzaldimino-4-androstene with the appropriate acid. Thus the acetate has been obtained as white crystals which analyze:

Calculated for CziHssOsN: N, 4.03%. N, 4.17%.

.Where the purity of the keto-amine salt is of Found principal concern, it is better of course, to begin the hydrolysis with recrystallized 3-keto-17- benzaldimino-4-androstene.

Example 4 To a hot solution of 10 g. of 3-hydroxy-17- amino-S-androstene in 70 cc. of ethanol was added a hot solution of 5.4-. g. of m-nitro-benzaldehyde in 70 cc. of ethanol. Crystals began to form after one minute. After several hours the mixture was filtered and the crystals were washed with methanol and dried. The yield was 14 g. of cream-colored plates of 3-hydroxy-17- (m-nitrobenzaldimino)--androstene melting at 198199 C. and giving the analysis:

- Calculated for CzsHseOsNz: C, 73.90; H, 8.11%. Found: C, 73.80; H, 7.96%.

E'aldmple 5 A solution of 5.8 g. of 3-hydroxy-17-amino-5- androstene in 100 cc. of hot methanol was 4 treated with a solution of 3.7 g. of p-bromobenzaldehyde in 50 cc. of hot methanol. After several minutes white flakes of the Schiffs base beganto separate. After cooling, the product was filtered and washed with methanol, then dried. The 3-hydroxy-17-p-bromobenzaldimino- 5=androstene so obtained melted at 252-253 C.

Example 6 Five grams of 3-hydroXy-17-p-bromobenzaldimino-5-androstene wa dissolved in 60 cc. of toluene and 20 cc. of cyclohexanone. A small amount of the solvent was distilled to remove traces of moisture, then a solution of 4 g. of aluminum isopropoxide in 25 cc. of hot toluene was added. After three hours heating, the mixture was cooled, diluted with ether, washed with 15% sodium hydroxide and with water, then steam distilled. The cooled residue was a hard yellow wax in water suspension. This crude 3-keto-17- p-bromobenzaldimino-4androstene may be used directly for further synthesis or it may be crystallized from ether plu methanol, from which it separates as yellow prisms meltin at about 193- 187 C. i

Example 7 Twenty grams of 3-acetoxyternorcholenylamine acetate, obtained, for example, by the Curtius degradation of 3-acetoxybisnorcholenic' acid,. was dissolved in 200 cc. of ethanol containing 6 g. of potassium hydroxide and 6 cc. of water.

' About half of the alcohol was distilled from the solution, then the residue was cooled, diluted with ether and the ether layer was washed twice with water to remove the alkali and salts. solution of 8 cc. of benzaldehyde in 50 cc. of ethanol was added to the ether solution, then ether was distilled slowly until the solution began to crystallize. The Schifis base separated as white flakes. Recrystallization from benzene plus ethanol gave crystals melting at 191 C. and giving the analysis:

Calculated for C28H39ON: C, 82.90; H, 9.69%. Found: C, 82.57; H, 9.31%, 7

Example 8 A solution of 15 g. of 3-hydroxy-20-benzaldimino-5-pregnene, prepared as described above in Example 7, and 30 cc. of cyclohexanone in cc. of hot toluene was distilled briefly to remove 10 cc. of solvent and a trace of moisture. To the residual hot solution was added 15 g. of aluminum isopropoxide in 50 cc. of hot toluene. The mixture was heated over a steam bath for three hours, then cooled, diluted with ether,

washed three times with 15% sodium hydroxide solution, three times with water, and then steam distilled. The residue was a suspension of waxy 3-keto-20-benzaldimino-4-pregnene in water. It may be'used' directly for further synthesis or it may be purified by crystallization from ether.

The recrystallized substance is pale yellow crystals melting at about 199-202 C.

Example 9 Five grams of 3-keto-20 benzaldimino-4-pregnene was dissolved in 20 cc. of 40% acetic acid, thenthe solution was steam distilled to remove benzaldehyde and acetic acid. The residual clear solution of the keto-amine acetate'wa concentrated and crystallized from a small volume of water. 3 Ireto 20 amino vgi-pregnene acetate 5. forms white crystalswhich melt with decomposition at 220-222 C. and which give the analysis:

Calculated for CzsI-InOaN: N, 3.73%. Found: N, 3.71%.

In a similar manner 3-keto-20-amino-4-pregnene hydrochloride was obtained as a white crystalline powder which decomposes at about 300 0., and gives the analysis:

Calculated for C21H34ONC1 /gH2OZ C, 69.86; H, 9.78%. Found: C, 69.54; .H, 10.00%.

The foregoing examples. are illustrative of the invention. Various changes and modifications may be made therein without departingirom the spirit and scope. of the invention. Thus other aromatic aldehydes. may be employed for the preparation of the S'chiiPs bases, and other salts prepared either directly or indirectly from the keto-Schiffs bases. Likewise, other steroid amines may be treated wherein there are other substituent groups on the nucleus, as well as those in which the 1'7 side chain may contain one or more methylene groups between the 20- carbon atom and the nitrogen, such as the norcholenylamines, cholanylamines and the like.

Having described the invention, what is claimed is:

1. The process which comprises reacting an aromatic aldehyde with a steroid amine having a hydroxy group in the 3-position and a substituent in the 17-position selected from the class consisting of the ---NH; group and allzyl radicals containing an NI-I2 group to form a Schiffs base, oxidizing the 3-OH group to a keto group and hydrolyzing the 3-keto-Schiffs base with an acid to form a 3-keto-amine salt.

2. The process of claim 1 in which the substituent in the 17-position of the starting steroid amine is the -NH2 group.

3. The process of claim 1 in which the substituent in the 1'7-position of the steroid amine is the group 4. The process of claim 1 in which the starting steroid compound is 3-hydroxy-17-amino-A androstene.

5. The process of claim 1 in which the starting steroid compound is 3-hydroxy-20-amino-A pregnene.

6. The process which comprises oxidizing the S-hydroxy group of a B-hydroxy steroid compound having a substituent at the 1'7-position selected from the class consisting of -N=CHR and -R'N=CHR groups, wherein R, is an aromatic group and R is an alkyl group to a keto group, and hydrolyzing the 3-keto-Schiffs base with acid to form a 3-keto-amine salt.

7. The process of claim 6 in which the substituent group at the 1'7-position of the 3-hydroxy steroid is a --N=CHR group.

8. The process of claim 6 in which the substituent group at the l'I-position of the 3-hydroxy steroid is group.

9. The process of claim 6 in which the B-OH radical is oxidized to the radical by treatment with an excess of ketone in the presence of and aluminum alkoxide.

10. 3-hydroxy steroid compounds. having. a. substituent group atthe. 1.7-positicn. selected from the: class. consisting1o-N==CHR and groups wherein R" is :a; monocyclicx aromatic. group;

11. The compounds-cfclaim 10 in which. the.-

substituent group at the 1'7-position is a; -N.=- CHE-group.

12; Compounds of the general formula.

where R; is a monocyclic aromatic group.

13. 3-hydroxy-l7-benzaldimino A androstene.

14. 3-keto-steroid compounds having a substituent group at the 17-position selected from the class consisting of --N=CHR. and

-N=CHR groups N=CHR where R is a monocyclic aromatic group.

18. 3-keto-17-benzaldimino-A -androstene. 19. Compounds of the general formula where R, is a monocyclic aromatic group.

20. 3-keto-20-benzaldimino-A -pregnene.

21. Theprocess of clairh 6 in which the acid usedis acetic acid.

22. Compounds of the androstene series char acterized by (1) the double bond involving the number 5 carbon atom, (2) the presence of an oxygenated substituent at the 3-position of molecular weight less than 18 bonded to the number 3 carbon atom through the oxygen atom, and (3) the presence of a N=CHR substituent at the 17-position, wherein R, is a monocyclic aromaticgroup.

23. Compounds of the pregnene series characterized by (1) the double bond involving the number 5 carbon atom, (2) the presence of an oxygenated substituent at the 3-position of mo- 15 lecular weight less than 18 bonded to the number 3 carbon atom through the oxygen thereof, and (3) the presence of a -N=CI-IR substituent at the 20-position wherein R. is a monocyclic aromatic group.

24. Compounds of the general formula wherein R is a monocyclic aromatic group 25. 3ehydroxy-izO-benzaldimino-A -pregnene. PERCY L. JULIAN. EDWIN W. MEYER. JOHN W. COLE.

ARTHUR MAGNANI.

20 No references cited. 

1. THE PROCESS WHICH COMPRISES REACTING AN AROMATIC ALDEHYDE WITH A STERIOD AMINE HAVING A HYDROXY GROUP IN THE 3-POSITION AND A SUBSTITUENT IN THE 17-POSITION SELECTED FROM THE CLASS CONSISTING OF THE -NH2 GROUP AND ALKYL RADICALS CONTAINING AN -NH2 GROUP TO FORM A SCHIFF''S BASE, OXIDIZING THE 3-OH GROUP TO A KETO GROUP AND HYDROLYZING THE 3-KETO-SCHIFF''S BASE WITH AN ACID TO FORM A 3-KETO-AMINE SALT. 